In the past, abrading wheels of this type have generally had a core of uniform thickness and diameter, to form the general shape of a disc, with tungsten carbide grit on the outer peripheral surface.
It has been found desirable to provide radial grooves or openings in the finished wheel. These grooves act as regions of accumulation for the material being removed and facilitate release of the material from the abrading wheel. Without the radial grooves or openings, the grit surface would tend to accumulate material and become packed with “dust”, thus reducing its ability to remove further material from the work piece, by clogging the interstices of the grit surface.
In the past, the radial openings have been formed by machining through the peripheral surface (or rim) of the disc-shaped wheel and into the central portion of the core. This is an expensive process; six radial grooves typically are formed in each abrading wheel. Moreover, the cutting process left sharp corners which provided regions for accumulating the residue of the abrading process, and created regions of stress in the wheel.